Production of calcium nitrate



Patented Jan. 10, 1933 :SPATIENT *DLFEFIGE OSCAR KASELITZ, OF BERLIN, GERMANY No Drawing. Application filed January 9, 1932, SerialaNo.=r585,803,1and'in.GermanyTebruary 24,1931.

My-invention refers to the production of nitrates of alkaline earth metals and more particularly calcium nitrate by the interac tion of basic calcium compounds with nitric acid ornitrous; gases. It is an object of my invention toavoid certain difiiculties encountered inthe usual methods-of producing calcium nitrate and to provide a simple and etficient procedure, by which a substantially anhydrous and substantially neutral product is 1 obtained.

It has'alrea-dy been proposed to produce nitratesofalkaline earth metals by treating the oxides,hydroxides or carbonates of such metals with liquid or vaporousnitric acid or with nitrous gases, and it has been found that it is advantageous to carry out these reactions at anelevated temperature so as to directly obtain a solid "final product. "It is, however, diflicultif not impossible to obtain in such way' aproduct which is practically'free from nitrites, moisture and-unconverted basic alkaline earth compounds.

In the course of my investigations,fI have ascertained that on treating the usual basic calcium compounds with nitrous gases or the like, thereaction cannot be brought to completion, unconverted particles remaining over evenafter a prolonged treatment with the nitrous gases. Moreover, if the temperatureis' further raised, the reaction mass is liable to sinterywhereby further amounts of the basic calcium compounds are prevented from being converted into calcium nitrate. Apart therefrom the volume of the mass is increased inthe course'of the reaction, the mass becoming impenetrable to the nitrous 'ases. g5 According to' the presentinvention I avoid these drawbacks by mixing the basic calcium compound with solid, molten or dissolved calcium nitratebefore subjecting it to the action ofnitrous gases or vapours of nitric acid. -Homogeneous mixtures are preferred, andit' has also been foundadvantageous to shape theimixture in the form of. granules, agglomerates, briquettes or the like before or the'nitric acid vapours.

rBy usingsuch a mixture, which-obviously .tage at temperatures of 300-3509. and at any vceed in various Waysdepending on thetype .of basic calcium compounds WlllCll are-tobe nitrate,or may be agglomerated K with :the aid -.of concentratedwaterysolutions of calcium contains some basic 7 calcium; nitrate formed by the interaction of the neutral calcium nitrate with calcium oxide, hydroxide or; carbonate, the speed of reactionis renderedmore uniform, an undue superheatingduring the .55

initialperiod ofthe reaction being avoided.

On the otherhand. such av mixture can. be readily and substantially completely converted int-o neutral calcium nitrate at temperatures as low as "200 Grand even at lower temperatures. .Idonotwish to limitrmyinvention. towa certain range of temperature, butl believe it'worth mentioning that the reaction maybe carried through with advanrate above200. C., whereby any water. contained .in the mixture is. evaporated. Nevertheless there is no danger ofsintering or, cak ing of the reaction mass, and'the'final product is substantially freefrom unconverted basic calcium compounds, from nitrates. and from .water,-.practically completelysoluble .in water and has, a neutral reaction. v

In carryingout invention. I may proconverted, into calcium. nitrate, and. on, the

type and concentration of nitric acidvapours or nitrous gases whichrareto be used, .I may use qulckhmeiand slake 1t wlth the aid of a watery solution of 'calclum nitrate, but

Inlay also impregnate; granulatedquicklime I :w1thmoltencalcium nitrate.

'Slaked lime may be mixdnvith solid pulverized calcium nitrate, in a similarmanner asdescribedin my copending application for Letters Patent of the United States Serial No. 578,662 entitled .FMiXedfertilizer. If calciiuncarbonate shallbe used lmay'powderiit andam-ix it with powdered :calclum nitrate ;-in such a case Ima-y itreatthe powdery mixtureunder stirri ng WllT-ll ,IlltllCl acid vapours or nitrous gases (forinstancethose obtained by the combustion "of, ammonia), the mixture: being highly ipen'etrahle to-xthecgases crzwapours. subjecting it to the action ofthenitrous gases LI :may, however,: alsoa agglomeraterlthe; powdered mixtu-rethus obtained in a-similar man mentioned above or form porous briquettes therefrom, which also react readily and completely without becoming impenetrable to gases.

Example 1 Limestone is powdered to obtain an average particle size below 0.1 mm. and agglomerated in a rotating drum at ordinary room temperature with the aid of regulated amounts of a concentrated watery solution of calcium nitrate, the moist crumbly mass first obtained being kept in motion until globular granules or agglomerates have formed. As a rule 9 parts by weight of limestone require 1 part of the calciumv nitrate solution to obtain suitable agglomerates which are subsequently dried and subjected to the action of nitrous gases at an elevated temperature until a substantially neutral product has been obtained.

The details of the agglomerating step are more fully described in my copending application mentioned above.

Example 2 Calcium hydroxide (slaked lime) is agglomerated'with the aid of a concentrate calcium nitrate solution substantially as described with reference to- Example 1 so as to obtain substantially globular agglomerates or granules of the size of peas or hazelnuts, which are then treated with nitric acid vapours or nitrous gases.

Example 3 100 parts by weight granular quicklime are slaked under stirring with 60 parts of a 40% calcium nitrate solution, until a practically homogeneous mass is obtained. This mass is filled into wooden moulds, where it solidifies to form briquettes. These briquettes are converted into substantially neutral'calcium nitrate by treating them with nitrous gases or with vapours of nitric acid.

Example 4 Granular quicklime is introduced into molten calcium nitrate to obtain granules which partly consist of basic calcium nitrate, and further treated with nitrous gases at an elevated temperature toobtain anhydrous neutral calcium nitrate.

Example 5 150 kgs. of agglomerates obtained from slaked lime and from a calcium nitrate solution substantially as described with reference to Example 2 are treated with nitrous gases obtained by the combustion of ammonia, the reaction temperature being gradually raised from 250 to 360 C. After a 50 hours treatment there are obtained 330 kgs. loose agglomerates having the shape of the original ones but consisting of anhydrous neutral calcium nitrate.

Example 6' 450 kgs. globular granules obtained by agglomerating powdery limestone with a calcium nitrate solution, as described with reference to Example 1, are treated, at a temperature of about 330-360 (1., with a current of humid nitrous gases obtained by the combustion of ammonia. After 120 hours there are obtained 730 kgs. of a product which consists of anhydrous neutral calcium nitrate and contains but small traces of contaminations;

Example 7 130 kgs. of a briquetted mixture obtained by introducing granulated quicklime (calcium oxide) into molten calcium nitrate as described with reference to Example 4, and briquetting the mixture, are treated with humid nitrous gases at a temperature of 250- 360 C. After 50 hours of such treatment there are obtained 320 kgs. anhydrous neutral calcium nitrate.

In the claims afiixed to this specification and forming part thereof the term basic calcium compounds is intended to designate calcium compounds such as calcium oxide, hydroxide, carbonate and the like which are capable of reacting with vaporous nitric acid or with nitrous gases, calcium nitrate being formed; the term nitrous ases including gases containing N0 or N preferably in mixture with oxygen and steam, as is usual in the art, and nitric acid vapours.

Various changes may be made in the details disclosed in the foregoing specification without departing from the invention or sacrificing the advantages thereof.

I claim 1. The method of producing solid calcium nitrate directly from basic calcium compounds comprising mixing such a basic calcium compound with calcium nitrate and treating said mixture with nitrous gases at an elevated temperature.

2. The method of producing solid calcium nitrate directly from basic calcium compounds comprising homogeneously mixing such a basic calcium compound with calcium nitrate and treatin said mixture with nitrous gases at an elevate temperature.

3. The method of producing solid calcium nitrate directly from basic calcium compounds comprising mixing such a basic calcium compound with calcium nitrate and treating said mixture with nitrous gases at a temperature above 200 C.

4. The method of producing solid calcium nitrate directly from basic calcium compounds comprising introducing granulated quicklime into molten calcium nitrate and treating said mixture with nitrous gases at an elevated temperature.

5. The method of producing solid calcium nitrate directly from basic calcium compounds comprising slaking quicklime with a watery solution of calcium nitrate, shaping the mixture thus obtained and treating the shapes after solidification with nitrous gases at an elevated temperature.

6. The method of producing solid calcium nitrate directly from basic calcium compounds comprising slaking quicklime with a watery solution of calcium nitrate, briquetting the mixture thus obtained and treating the briquettes after solidification with nitrous gases at an elevated temperature.

7. The method of producing solid calcium nitrate directly from basic calcium compounds comprising mixing powdery calcium carbonate with calcium nitrate and treating the mixture thus obtained with nitrous gases at an elevated temperature.

8. The method of producing solid calcium nitrate directly from basic calcium compounds comprising mixing powdery calcium carbonate with a regulated quantity of a watery solution of calcium nitrate, keeping the criunbly mass thus obtained in motion until granular agglomerates have formed and treating said granules with nitrous gases at an elevated temperature.

In testimony whereof I aflix my signature.

OSCAR KASELITZ. 

